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SCREW CUTTING MAGHINB.

Patented Nov. 1, 1887.

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No. 372,434. Patented Nov. 1, 1887.

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SCREW CUTTING MACHINE.

No. 372,434. Patented. Nov. 1, 1887.

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UNITED STATES PATENT OFFICE.

THOMAS BENJAMIN SMITH, OF VEST BROMETIOH, COUNTY OF STAFFORD, ENGLAND.

SCREW-CUTTING MACHINE.

SPECIFICATION forming part of Letters Patent No. 372,434, dated November 1, 1887.

Application tiled February 14, 1887. Serial No. 227,643. (No model.) Iatcnted in England April 24, 1886, No. 5,641.

To all whom it may concern.-

Be it known that I, THOMAS BENJAMIN SMITH, of Vest Bromwieh, in the county of Stafford, England, screwmaker, and a subject of the Queen of Great Britain, have invented a certain new and useful Improved Screw- Outting Machine, (for which a Patent No. 5,641, dated April 24, 1886, has been granted to me in England;) and I do hereby declare that the following is a sufficient description of the invention to enable those skilled in the art to which it appertains to carry the same into practical effect.

This invention has for its object improvements in screw-cutting machines which are much quicker in their action than those now in use, and the screw is cleaner when made.

I mount upon asuitable circular plate three, four, or more slides radiating toward the cen- 2o ter of the plate, and each slide carriesacurved cutter which operates upon the screw to be cut.- This plate is carried up a hollow tube from the back thereof, so that the screw can pass nside as it is being cut. At the back of the plate and upon or against the tube I form jaws, one for each slide, in which I hang 1evers, the front end of each lever piercing the back of the plate and entering a suitable recess in the back of its slide, and the other ends are provided with jointed knuckles carrying friction-wheels, which may be set and adjusted by set-screws to a great nicety, and these wheels are kept against the spindle by a circular or other spring. Upon the back of the tube I place asliding collar, which may be operated byalever or other means, and the front end is made conical or other shape, so as to be one circular wedge, so that as it is forced forward against the said friction-wheels on the back end of the levers they are turned in the jaw upon their pivots, and so the slides, whether three, four, or more, are operated thereby, which carries the cutters against the pin upon which the screw is to be cut, and

each cutter advances at the same speed by means of the circular collar-wedge, and they exactly balance each other in their action, thus preventing friction or even turning it into account in assisting to form the thread.

In order that my invention may be clearly understood and easily carried into practice, I

have appended hereunto two sheets of drawings, upon which are illustrated not only the parts thereof which form the subject of myin Vention, but also a sufficient number of other parts to enable me to more fully explain the action of my invention when applied to screw machinery in general.

Figure l is a front elevation of my machine, in which the following parts are important to my invention, viz: the circular plate A with its mountings, the hinged levers F, and the pointer C. The particular mode of operating these principal parts are further illustrated in detail.

Fig. 2 shows an enlarged longitudinal sectional View of the hinged levers F in their normal positions, about parallel to the tube M, and therefore with the cutters Qaway from the work-4'. 6., away from the blank I.

Fig. 3 is an elevation of the circular plate A, with the cutter-slides G and the cutterholders H removed, so that the method of tightening up the slides by the screws J upon the adjustable pieces J are distinctly seen, as 7 steadiness in holding the sliding cutters is very important.

Fig. at is front elevation of the plate A, as seen at Fig. 2, with the cutters Q Q Q (2f all in position upon their holders II and slides G and ready for work.

Fig. 5 is a cross section through the cutterholders H and cutters Q.

Fig. 6 is a plan of the pointer O withdrawn from the tube M.

Fig. 7 is a longitudinal section through the pointer 0, showing how the pointing-tool L is fixed in O by the screws L, and Fig. 8 is a cross-section of the same.

Fig. 9 is a similar longitudinal section ofthe 0 parts most important to my invention, but with the levers F moved into an angular position to the tube M, by which the cutters Q are brought into cutting contact upon the blank \V, as will be hereinafter more fully explained. 5

Fig. 10 is a plan of the machine in diagram form for the purpose of showing how the parts may be operated or driven, which do not in general arrangement form a part of my invention, as it will be obvious that these may be greatly varied in arrangement.

The machine is self.- contained upon the bed T, and the head portion, Figs. 2 and 9, which forms the principal part ofmy invention, is supported upon the tube M, this tube being carried by the head-piece T of the bed T in such a substantial manner as to become practicallya part ofit. Upon the right-hand end of the tube M is fixed the circular plate A, in which theslides G are set, and these slides require to work very steady and dead true, and I therefore arrange the side pieces,J,

to set up by the screws J. against the slidesG,

so as to keep them exceedingly steady. These slides G carry upon them the cutter-holders H, to which the cutters Q, are securely screwed, and the cutters are operated by the pivoted levers F, which are a very important part of my invention. These levers F are hung by suitable jaws formed upon them by the pivots f 2 to the projections m,which are formed upon the tube M, and the nose of each lever carries a friction-roller, F,which operates in the H01- low of suitable projections, g, which are fixed to or a part of each of the slides G. To the other end of each lever F is hung the adjustable arms t on the pivots It, each of which carries a friction-roller, E, these armst being adjustable to the greatest nicety-by means of the screw-pins V. The levers F are opened at the left end by means ofthe slidingblock or circular wedge piece D,which is carried forward atthe desired moment by means of any suitablelever, d,worked from abeveled face-block, d, by the shaft U, which carries the slides G inward to form the thread upon the blank W. The levers F are automatically withdrawn by any suitable spring barrel, S. The pointer O is brought forward to cut the point of the blank W, as shown at Fig. '7 by the lever c, operated also from the shaft U by the beveled face-block c and the pointer is withdrawn by the spring 0.

The action is briefly as follows: The screwblank W, upon which the screw is to be cut, is delivered into the jaws N, Fig. 1, which are made to grip it by the action of the loose collar O, which is brought forward upon the shaft by the cam-motion O, worked'from the time behind the projection at P.

second shaft, U, and, as the shaft P is made to .IIIOVG longitudinally, it is held back during with the screw-blank W, which at this time is revolving,and the pointing being'done by the edge Z of the tool L, which is contained in the pointer 0, Fig. 7, after which the pointer retreats. Two motions then simultaneously occur:

First. The shaft P is moved longitudinally wedges open the friction-wheels E by means of the levers F, which are pivoted at f, and are connected by the ball-bearing F to the cutterslides G, and thereby operate the cutters Q, Q,

Q, and Q upon the screw-blank W, which at the same time is being brought forward by the shaft P, as before described. The circular wedge then retreats and the cutters open again by means ofthe circular spring or other device, S, pressing the reverse ends of the levers F together, and at the same time the weight 2 is raisedby means of the cam 4 and lever 3 and opens the regulator R and jaws 4", thereby releasing the shaft, which is then brought back to its original position by the cam O at the same time as the screw is released by the collar O.

The one pulley Xandbevel-whee1Z are provided with a fixed key,which slides in agroove formed on shaft P, so as to allow it to move longitudinally.

It will be understood that the jaws N, shaft 1?, and, indeed, the whole of the back working parts and gear, together with any mode of feeding which may be used, do not form a part of my invention, which is confined to the mode of cutting the thread shown at the left-hand part of drawing-'1 and in'greatcr detail on drawings 2 and 3.

What I claim, then, is-

I. In screw-cutting machinery, the combination of the levers F with the tube M, the sliding cutters Q, and the wedge-piece D, operating substantially as and for the purpose herein set forth.

2. In screw-cutting machines, the levers .F,

' withthe adjustable heel-pieces t, for finely setting the depth of each particular cutter, as set forth.

3. In screw-cutting machines,, the pointer O, in combination with the tube M and the lever c, said pointer being carried inside said tube and operated by said lever for forming the points of the blanks'W before the thread is cut therein, as set forth.

4. In screw-cutting machines, the combination of the levers F, tube M, and pointer G with the cutter-plate A, substantiallyas set THOMAS BENJAMIN SMITH.

Witnesses:

GEORGE PRreE, GEORGE BARKER. 

